1. Field of the Invention
The present invention relates to a power converter and, more particularly, to a stepped waveform VSCF converter which can be used either as an electrical power source that accepts variable frequency, variable voltage, AC power and provides constant voltage, constant frequency, AC power or as a start converter that starts main or auxiliary engines from an AC source with minimal disturbance to the input power quality.
2. Description of the Prior Art
There are a wide variety of VSCF power converters that provide a constant frequency, constant voltage, from a variable frequency, variable voltage, obtained from an AC synchronous generator mounted on the prime mover (main or auxiliary engine). However, very few VSCF converters have start capability to start the AC synchronous generator and, in turn, the prime mover. If a VSCF converter has this capability, it has been found to either pollute the input source and degrade input power quality or an extensive reconfiguration of the power converter, with power contactors between generate and start operation mode, has been required. This is described in U.S. Pat. No. 4,968,926 issued to Dhyan Chand. The use of such converters increases weight and decreases reliability.
It is an object of the present invention to incorporate, with minimal modification, generate and start features into a 24-stepped waveform VSCF converter. The present invention will provide improved power quality therefore taking advantage of common components such as transformers and semiconductors.